He walked in,carrying a book in his hand,went to a table near the window_sat down in silence.A then B.and C.but 请给出解题详情.
问题描述：
He walked in,carrying a book in his hand,went to a table near the window_sat down in silence.A then B.and C.but 请给出解题详情.
答
b怎么不选then?它应该是并列关系